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Biomedical subjects

R Hawkins

Publications and source records attributed to R Hawkins.

At least 109 records · Page 6Linked to original sources
PubMed1984

Ultrasound survey of gallstones and other hepatobiliary disorders in patients with Crohn's disease.

Abdominal ultrasound was performed in conjunction with liver function tests in 38 patients with small bowel Crohn's disease and a similar number of age- and sex-matched healthy controls. Five (13%) patients had had previous cholecystectomies for cholelithiasis, and eight (21%) were found to have gallstones on ultrasound. Thus, a total of 34% of patients as compared with 8% of controls had gallstones (P less than 0.01). Compared with 8% of controls, 53% of patients had evidence of at least one biochemical or ultrasonic hepatobiliary abnormality (P less than 0.001). A bright liver echo pattern may be indicative of portal triaditis. The high prevalence of gallstones in Crohn's disease should be considered in any patient who continues to complain of abdominal pain despite otherwise appearing to be in remission.

Adult↗
PubMed1983

Chronic infusion of angiotensin II into the olfactory bulb elicits an increase in water intake.

Chronic infusion of angiotensin II (ANG II) into the olfactory bulb (OB) elicited a moderate dipsogenesis which occurred only during the dark phase, essentially doubling the water-to-food intake ratio. Removal of the food from the ANG II-OB group reduced water consumption to the level of the saline-infused/food-deprived controls. These experiments suggest that ANG II may interact with the OB to alter the normal water/food relationship.

Angiotensin II↗
PubMed1983

Tetrachlorophthalic anhydride asthma: evidence for specific IgE antibody.

We describe seven women with asthma induced by occupational exposure to an acid anhydride, tetrachlorophthalic anhydride (TCPA), an epoxy resin hardening agent. Inhalation tests with TCPA at atmospheric concentrations of less than one tenth of a manufacturer's recommended exposure limit provoked asthmatic reactions in the four women tested. None had evidence of pretest bronchial hyperreactivity. Immediate skin prick test reactions were elicited in the seven subjects by a conjugate of TCPA with human serum albumin (TCPA-HSA) but not in others tested. Specific IgE antibody levels to TCPA-HSA, measured by radioallergosorbent test scores, were significantly elevated in the seven, but not in TCPA-exposed and unexposed comparison groups. These results imply that occupational asthma caused by TCPA is an allergic reaction mediated by specific IgE antibody.

Adult↗
PubMed1983

Substrates of energy metabolism of the pituitary and pineal glands.

The capability of the neurohypophysis, the adenohypophysis, and the pineal gland to oxidize nonesterified fatty acids and glucose as energy sources was studied in vivo. Fed and 48-h-starved rats had catheters placed in their femoral vessels. After they became conscious, an intravenous injection of one of the following was given: [1-14C]acetate, [1-14C]octanoate, [1-14C]-palmitate, or [2-14C]glucose. After 5 min the rats were sacrificed. These metabolites produce [14C]acetyl-CoA within the mitochondria when they are oxidized as metabolic fuels. On passage through the Krebs cycle a considerable portion of the 14C is trapped in large amino acid pools closely associated with the Krebs cycle; the appearance of 14C in these amino acids was taken as evidence of oxidation. As expected, brain structures behind the blood-brain barrier (cerebral cortex and caudate) showed considerable labeling of Krebs cycle-associated amino acids in both nutritional states when [2-14C]glucose was the substrate. Surprisingly, however, no label was detected in amino acids of the neurohypophysis or the pineal gland in starved rats and very little in fed rats. On the other hand, 14C from acetate and palmitate was extensively incorporated into amino acids of the pineal gland and the neurohypophysis, while little 14C labeling was found in the cerebral cortex and the caudate. Octanoate, which passes the blood-brain barrier readily, labeled amino acids of all tissues. The experiments demonstrated conclusively that the neural structures studied, which have no blood-brain barrier, do not rely heavily upon glucose as a fuel for oxidative energy metabolism, in contrast to the rest of the brain. The results also showed that nonesterified fatty acids may supply at least some of their energy requirements.

Animals↗
PubMed1982

Lithium delays biochemical circadian rhythms in rats.

Recent evidence has indicated that a fast circadian oscillator or pacemaker might contribute to affective illnesses, particularly manic depressive disease. In order to test the hypothesis that lithium exerts its therapeutic effect by slowing or delaying overly fast circadian rhythms, 95 rats were fed a lithium-containing diet for a period of 3-4 weeks, and 91 rats were fed a control diet. The animals were sacrificed at times around the clock. Eight of the eleven substances measured (plasma prolactin, PTH, corticosterone, and aldosterone, serum calcium and magnesium, and cerebellar calcium and magnesium) showed large delays in their circadian rhythms in the lithium-fed rats. This supports the hypothesis that lithium's therapeutic action is to delay overly fast circadian rhythms.

Animals↗
PubMed1982

Studies of the functional significance of angiotensin II receptors in the rat olfactory bulb: evidence for alterations in normal fluid intake.

The effects of continuous infusion of angiotensin II (ANG II, 1 microgram hr-1) into the olfactory bulb (O.B.) were studied on rats with chronically indwelling intracerebral cannulae. Chronic infusion (ALZA minipump system) of ANG II into the O.B. elicited a moderate dipsogenesis as compared to saline infused animals. The increased drinking occurred only during the dark phase (6 pm - 6 am) and appeared to be associated with food intake, which also occurred during this time. Removal of the food or disconnection of the minipump reduced water consumption to comparable levels in both groups. Acute injection of ANG II (250 ng) into the O.B. failed to elicit drinking. Since the olfactory bulb has a high concentration of ANG II receptors, these experiments suggest that ANG II may interact with the O.B. to facilitate the drinking associated with food intake.

Angiotensin II↗
PubMed1981

Occupational asthma in a factory making flux-cored solder containing colophony.

The prevalence of work-related wheeze and breathlessness was measured in factory employees manufacturing flux-cored solder. The flux contained colophony which was heated in the production process, exposing the workers to colophony fumes. Measurement of colophony in the breathing zone defined three grades of exposure with median levels of 1.92 mg/m3 (six subjects), 0.02 mg/m3 (14 subjects), and less than 0.01 mg/m3 (68 subjects). All but two workers in the first two groups, and 90% of a random sample of the last group, were studied. Occupational asthma was present in 21% of the higher two exposure groups and 4% of the lowest exposure group. Mean values of FEV1 and FVC fell with increasing exposure. The prevalence of upper and lower respiratory symptoms was only one-third to a half that found in a previous study of shop floor electronics workers, whose work raised the flux to a higher temperature and produced higher concentrations of colophony fume. Total IgM levels were higher in the solder manufacturers than in unexposed controls, and were higher still in the electronics workers. The solder manufacturers were exposed to colophony fumes at 140 degrees C, below the temperature at which the resin acids decompose, supporting the hypothesis that it is the whole resin acids rather than decomposition products which cause occupational asthma. The threshold limit value should be based on the resin acid content of the fume, and not the aldehyde content as at present. The survey suggests that sensitisation will not be prevented unless exposure is kept well below the present threshold limit value.

Adult↗
PubMed1980

Occupational asthma in a research centre breeding locusts.

The prevalence of work-related asthma, rhinitis and urticaria was measured in a scientific establishment working with locusts. Twenty-six percent of those handling the locust in the research centre had work-related wheeze or breathlessness, and one-third had work-related rhinitis and urticaria. Work-related symptoms were uncommon in scientists exposed to locusts in the field, and in other employees at the centre. Antigens were prepared from the locusts, Schistocerca gregaria and Locusta migratoria, as well as the moth, Chilo partellus, which was also bred at the centre. Skin prick testing with the locust antigens showed positive reactions in 55% of the atopic workers at the centre, but were also present in 43% of unexposed atopic workers. In this latter group there was a correlation between positive reaction to locust and dermatophagoides antigens. Atopic workers handling the locusts developed occupational asthma more often and more quickly than similarly exposed non-atopic workers. IgG and IgE antibodies to the locust antigens were found to correlate significantly with both the degree of exposure and the presence of disease.

Antibody Specificity↗
PubMed1979

Occupational asthma in an electronics factory.

Workers in a modern electronics factory were surveyed by questionnaire and lung function testing to see if there was evidence of widespread work-related respiratory symptoms. Of the responding workers exposed to solder flux fumes on the shop floor, 22% had work-related breathlessness or wheeze or both. Exposed workers had a lower FEV1 and FVC than unexposed workers. Work-related rhinitis was also present in 22% of exposed workers. The most likely cause for these results is sensitivity to colophony fumes, released from solder flux during soldering. Levels of solder flux fume were below the threshold limit value in this factory during the survey.

Adult↗